The most common designation for the terms "solar energy", "wood energy", "hydropower" and "wind energy" is to a group of resources that we designate as "alternative energy". The common view is that fossil fuels and nuclear energy are the primary energy resources, and anything different from them is an alternative that should be given little consideration. This view, though, is fairly recent in the history of mankind. For most of the time that mankind has been using energy other than muscle power, these "alternative" sources of energy have been the predominate source of energy. Three thousand years ago, these "alternative" forms of energy were used to grind grain, heat homes, transport themselves, and cook meals. It has only been within the last 150 years with the invention of the drilling rig and the fission reactor that "alternative" sources have fallen by the wayside.
This relegation to alternative energy status has occurred, mostly, because of economics. As technology increased for the exploitation of fossil and nuclear fuels, their prices have plummeted to historical lows. In light of the cost differences that range from 2-5 times that of fossil fuels or nuclear, most folks have opted away from alternative fuels. However, these economic costs are not the only costs that come with using an energy source. The costs of pollution and diminished resources are rarely factored into the equation, and we have been paying a price for having not considered them. As these costs have increased, and as technology has lowered the price of producing energy in these "alternative" ways, people are beginning to give them a new look.
For the rest of this discussion, we are going to group these resources into a more appropriate term: renewable energy. Wind, solar, and water all have the property that the use of them does not deplete their quantity.
This module will look at the science behind renewable energy, the methods used to generate electricity from it, and the changing economics of the situation.